Surgical knife having malleable shank

ABSTRACT

A surgical knife for removing meniscus from human knee joints or the like and adjacent the concave surfaces of the tibia, for example. The knife has a malleable shank portion which can be shaped by the surgeon as surgery progresses so that the blade at the end of the shank can be directed accurately in the desired path of the incision without damaging the articular cartilage, veins, nerves or arteries. The surgical knife also includes a hinge in the shank portion which permits the sharp blade to be turned in the desired location within the incision, and this actuation is accomplished by a mechanism in the handle of the knife and under full and accurate control of the surgeon.

[ Oct. 28, 1975 1 SURGICAL KNIFE HAVING MALLEABLE SHANK [76] Inventor:George McGuire, Rte. 3, Orange Lane, DePere, Wis. 54115 22 Filed: Nov.14, 1974 211 Appl. No.: 523,693

[52] US. Cl. 128/305; 30/321; 30/356 [51] Int. Cl. A61B 17/32 [58] Fieldof Search 128/305; 30/320, 321, 356

- [56] References Cited UNITED STATES PATENTS 2,029,495 2/1936 Lowe128/305 3,221,744 12/1965 Stryker 128/305 3,252,210 5/1966 Bowden 29/213E UX 3,832,771 9/1974 Morgan 30/320 X FOREIGN PATENTS OR APPLICATIONS663,074 7/1938 Germany 128/305 373,517 1/1964 Switzerland 128/305 OTHERPUBLICATIONS Leggiadro, A Flexible Meniscotomy Knife, IN Jour.

of Bone and Joint Surgery, 40A 933-934, 1958.

Primary ExaminerChanning L. Pace Attorney, Agent, or Firm.lames E.Nilles [57] ABSTRACT A surgical knife for removing meniscus from humanknee joints or the like and adjacent the concave surfaces of the tibia,for example. The knife has a malleable shank portion which can be shapedby the surgeon as surgery progresses so that the blade at the end of theshank can be directed accurately in the desired path of the incisionwithout damaging the articular cartilage, veins, nerves or arteries. Thesurgical knife also includes a hinge in the shank portion which permitsthe sharp blade to be turned in the desired location within theincision, and this actuation is accomplished by a mechanism in thehandle of the knife and under full and accurate control of the surgeon.

14 Claims, 13 Drawing Figures US. Patent Oct. 28, 1975 Sheet 1 of 3 US.Patent Oct. 28, 1975 Sheet2of3 3,915,169

US. Patent Oct. 28, 1975' Sheet3of3 3,915,169

\E a X FIG. 9 57 //AC 12 m MC 33 Ac BACKGROUND OF THE INVENTION Thepresent invention pertains to surgical knives of the type, for example,for the removal of the meniscus SUMMARY OF THE INVENTION The presentinvention provides a surgical knive having a malleable shank which maybe shaped by the surcartilage, commonly'referred'to as meniscus in theknee joint in case of damage or disease of the structure,

such as the torn cartilage? of the athlete. This surgical procedure isusually done from the front of the knee through a relatively smallincision, the size of the incision being limited in its extent by theadjacent supporting ligaments which may not be cut. As a result, it ispossible for the surgeon to see only the front portion of the meniscuscartilage and he must remove the back portion as a blind procedure. Asurgical knife must be passed into the back of the knee beyond thevision of the surgeon and the entire meniscus cartilage excised.

In the event the knife is passed too far forwardly, a portion of themeniscus cartilage remains and that may require a second operation forits removal. On the other hand, if the knife passes too far to the backof the knee, the main vessels to the lower leg may be severed and if notrepaired, the patient may lose his foot and lower leg. In addition tothe above problems, this surgical procedure must be accomplished withoutin any way scratching the articular cartilage which covers the femur andthe tibia and which is so soft that it may be marred by a fingernail, itcannot repair itself, and the fissure may initiate an ultimate breakdownof the entire surface. This is known as traumatic arthritis.

The above surgical procedure is further complicated by the fact thatwhen the knife is near the termination of the excision at the back partof the meniscus, it should then be turned towards the front of the kneeso as to sever that part of the meniscus located and attached at therear of the knee, but this is not possible with any prior art knives ofwhich I am aware. One conventional means for severing this meniscuscartilage at the back part of the knee is to make another small incisionthrough the back of the knee joint, but this is undesirable andincreases the amount of permanent damage to the ligaments, increases thepatients pain and lengthens the time of recovery.

Prior art knives of the general type to which the present inventionrelates are shown in the U.S. Pat. No. 2,029,495 to Lowe, issued Feb. 5,1936 and the U.S. Pat. No. 3,221,744 to Stryker of Dec. 7, 1965. Both ofthese knives utilized a rigid shank which was permanently curved at itsouter end in an attempt to have the blade follow the desired path ofincision around the convex portions of the knee joint. Knee joints ofvarious people are of different sizes, for example, the joint of a manpresents an arcuate path of much greater radius than the joint of achild. As a result these rigid construction prior art knives wouldeither dig into the bone and articular cartilage of the joint or in somecases would damage the vessels and nerves at the rear region of the kneejoint.

Furthermore, these knivesmust be razor-sharp for every operation becausethe meniscus cartilage, due to its micro-structure, cuts with ease witha sharp edge, but will not cut at all if the instrument is somewhatdull. Consequently, it is desirable in view of the limited use and costconsiderations of these knives that the knife be of the disposable type,at least in part.

geon as the incision process progresses so that the cut ting edge of theblade. is properly directed along its intended path of incision withoutdamage to adjacent parts-The knife provided by the present'inventionpermits the surgeon to have accurate control of the cutting edge of theblade even though it is located at a remote location in the knee jointor the like and out of vision of the surgeon; Another aspect of theinvention relates to a surgical knife of the above type which has ahinged or articulated blade and which is under positive and accuratecontrol of the surgeon even though the blade may be located remotelywithin the incision.

The knife provided by the present invention has a disposable portionincluding a malleable shank formed of low density polyethylene which canbe formed into various shapes without breaking or returning to itsoriginal shape The blade and the means for actuating the hinged bladeare imbedded by being molded in the polyethylene shank. The assembledshank thereby forms a disposable portion of the knife and insures that asharp blade is provided for each operation at an en- .conomical cost.Forwardly extending probes are integrally formed with the shank portionand of polyethylene so as to shield the knife and aid it in properlyfollowing its intended path of incision. The polyethylene portion of theknife is soft and of low density and will not scratch or damage theparts of the body adjacent the incision. Furthermore, the polyethylenewill not v ent invention will appear hereinafter as this disclosureprogresses, reference being had to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view of aknife made in accordance with the present invention, certain parts beingshown in section, the sectional portion bein taken generally along theline 1-1 in FIG. 2;

FIG. 2 is a view of the knife shown in FIG. 1 and taken generally alongthe line 2-2 in FIG. 1;

FIG. 3 is a view of the core, blade, and tensioning means of the knifeshown in FIGS. 1 and 2;

FIG. 4 is a view of the core, blade, and tensioning means and takengenerally along the line 4-4 in FIG.

FIG. 5 is a view similar to a portion shown in FIG. 2, but showing theblade when the tensioning means has caused it to swing to a positionapproximately from FIG. 7 is an enlarged, fragmentary, perspective viewof the blade and of the knife shown in FIGS. 1, 2 and FIG. 8 is aperspective, exploded view of the knife made in accordance with thepresent invention;

FIG. 9 is an elevational view in section of a human knee and with theknee bent at an angle of about 90;

FIG. 10 is a plan view of the tibia shown in FIG. 9, the view beingtaken generally along the line 10l0 in FIG. 9;

FIGS. 11 and 12 are views similar to FIG. 10 but showing the knife ofthe present invention in various positions while the incision is beingmade;

FIG. 13 is a view similar to FIG. 12 showing the position of the knifewhen its incision is completed and when the blade has been flexed tosever the meniscus.

DESCRIPTION OF A PREFERRED EMBODIMENT A knife made in accordance withthe present invention is shown in FIGS. 1-8 inclusive and includes ahandle portion 1 having a trigger 2 shiftably mounted thereon as beingpivoted on the shaft 3. A thumb screw 4 extends through an arcuate slot5 in the handle and is threadably engaged in the tapped hole 6 of thetrigger. A hole 7 receives a tension member, such as a flexible wire 8which is held captive in its proper position in the trigger by means ofthe thumb screw 4.

The knife also includes a shank 12 which is molded from malleablematerial, preferably soft, low density polyethylene. The shank 12 has ametal core 14 molded and extending therein and this core may be ofstainless steel, brass or other metals. Also molded within the shank 12is the tension means or wire 8. The rear end of the core 14 is insertedin a recess 15 in the handle and the rear end of the shank 12 isinserted in the recess 16 and abuts against the shoulder 17 formed inthe handle. The shank is held in place by the wire which is held by thethumb screw and is also held by the clamp action of the two halves ofthe handle. The shank and its associated parts may thus be removed fromthe handle when the thumb screw 4 is loosened to free the end of thewire 8. It will be noted that the shank is generally formed with a crosssectional shape of a triangle having round corners.

At the other end of the shank is located the metal blade 20 which has asharpened front edge 21. The blade 20 is brazed, soldered, welded orotherwise rigidly secured to the metal core 14. This blade is preferablyformed of spring steel so that it can flex and thus form a hinge jointin the shank. For this purpose, the shank is formed with a traversenotch 24 adjacent its front end so that it can flex to a desired angle,for example, to the position shown in FIG. 5, when the wire 8 is pulledin the direction of the arrow. The front of the blade and of the shankis also formed with a pair of transversely spaced and substantiallyparallel .probes 26 and 27 which extend from the end of the knife. Theseprobes are formed integrally with the shank from the said malleablematerial such as low density polyethylene. It will be noted that theprobes are located at each end of the blade so as to shield the latteras the knife is being used. These blunt probes shield the blade andprevent the knife from penetrating outside the joint and also serve toguide the meniscus into the blade, as will appear.

The blade 20 also has a hole 28 therein which receives the hooked end ofthe wire 8.

The present invention finds particular utility when operating on a kneejoint, that is to say, in operating to remove the meniscus cartilage MCwhich has been damaged in the knee joint and which is located just abovethe concave surfaces of the tibia. As shown in FIGS. 9 to 13, the humanjoint of the knee includes the femur 31 and the tibia 32 having concavesurfaces 33 and 34. Both the femur and tibia are covered with articularcartilage AC which can be damaged. FIG. 9 shows the knee joint whenviewed from the front and when it is flexed to a bent or angle. FIGS. 10to 13 inclusive are top views of the tibia. It is at this front side 35of the tibia that the surgeon makes the initial incision 36 and 37 andthrough which incision the surgeon inserts the present knife. At therear side of the leg, that is at the rear side of the knee joint arelocated an artery 40, a vein 41, and nerves 42. As shown in thesefigures, the meniscus cartilage MC has attached ends 47 and 48 locatedat the front of the knee and also attached ends 50 and 51 located at therear side of the knee. The front ends of the meniscus cartilage can bereadily served by the surgeon and by visual observation simply byinserting a conventional surgical knife through the opening formed byincision 36 and 37. The meniscus cartilage MC also lies between thetibia and femur, as clearly shown in FIG. 9.

It is a difficult task however to sever the attached ends 50 and 51which are located to the rear of the knee joint and out of vision of thesurgeon and it is to this particular problem that the present inventionis directed.

In order to sever the ends 50 and 51 of the meniscus, the surgeon mustinsert his knife around the joint and along the track or path indicatedgenerally by the dotted lines 55. This path is located adjacent thearticular cartilage which covers the tibia and femur. The articularcartilage is extremely soft and can be marred and damaged by theslightest irritation such as a fingernail. This articular cartilagecannot repair itself and a fissure initially will cause breakdown in thesurfaces, resulting in traumatic arthritis. Consequently, it isnecessary that the surgeons knife does not damage or in any way abusethe articular cartilage by contact with it in case the blade is directedinwardly too far from its intended path of travel. On the other hand,the blade upon reaching the rear side of the knee, must not moveoutwardly so as to come in contact with the arteries, veins,

or nerves, by passing too far outwardly from the joint. 1

During the first portion of the knifes travel in the intended path 55,the incision is under the visual observation of the surgeon through theopening formed in the front side of the knee. However, as the knifepasses the ligaments 57 or 58 approximately half-way along the side ofthe knee, further fisual observation of its course of travel isprecluded. Heretofore, the prior art knives used in such an operationwould inadvertently either dig inwardly and into the articular cartilageof the joint or would extend outwardly at the rear end of the knee,thereby damaging the arteries, veins, or nerves.

The knives used in such an operation must therefore follow an arc ofover and are confined to this path by the ligaments on the outside andthe surfaces of the articular cartilage on the tibia and femur. The sizeof the knee obviously varies from patient to patient. Another problem isthe fact that the meniscus cartilage at the rear of the knee must besevered at the proper location, that is to say, if the knife passesprematurely through the meniscus, a portion of the meniscus remains andmay require a second operation for its removal. If however the knifepasses the meniscus too far to the backside of the knee, the mainvessels to the lower leg may be cut.

The knife provided by the present invention overcomes the abovementioned dangers and difficulties and permits the surgeon to shape themalleable shank of the knife as the surgical procedure progresses. Inother words, the surgeon may periodically withdraw the shank from theincision which is being made and then bend or shape the malleable shankso as to cause it to conform to the intended path 55 of travel. Duringthe passage of the knife in the joint, the rounded probes 26 and 27 actto guide the blade end of the knife while the blade acts to sever themeniscus, thus forming the The various stages of such a surgicalprocedure are shown in FIGS. and 13. When the blade has reached theposition shown approximately in FIG. 12, the surgeon begins to pull thetrigger 2 to pull the tension means 8 thereby causing the blade to flexor turn, and then when the end of the blade continues to travel andreaches the position shown in FIG. 13, the flexing action of the knifeedge has severed the attached ends 50 of the meniscus cartilage.

The surgical knife provided by the present invention permits the surgeonto control the direction of travel of the blade during the entire pathof the incision. The knife shank can be readily shaped for anyparticular size knee thus preventing damage to adjacent parts. The knifewill not scratch the articular cartilage and it can be controlled so asto accurately cut the meniscus cartilage along the proper path and atits attached, rear end. The malleable shank can be readily shaped by thesurgeon as the surgery progresses but it is rigid enough to enable it todirect sufficient force on the blade to cause the latter to cut themeniscus.

I claim:

1. A surgical knife comprising, a malleable shank having a metal coreextending therein, a cutting blade on one end of said core and having acutting edge adjacent one end of said knife, said knife also having ahandle portion at the other end of said shank, said shank being shapableby hand to conform to the desired path of movement of said blade duringsurgery.

2. The knife set forth in claim 1 including a hinge formed in said shankfor swingably mounting said blade.

3. The knife set forth in claim 2 further characterized in that saidhinge is formed by a transverse notch in said shank which permits saidcore to bend.

4. The knife set forth in claim 1 including spaced and substantiallyparallel probes extending from said one end of said knife and formedintegrally with said shank, said probes being located at each end ofsaid blade so as to shield the latter.

5. The knife set forth in claim 1 further characterized in that saidshank is molded of low density polyethylene.

6. A surgical knife comprising, a malleable shank formed of malleablematerial, said shank having a metal core extending therein, a steelblade fixed to one end of said core and having a cutting edge adjacentone end of said knife, a hinge formed in said shank for swingablymounting said blade, tension means connected to said blade and extendingalong said core for swinging said blade relative to said shank; saidcore, blade and tension means being encapsulated in said malleablematerial and being molded therein, said knife also having a handleportion at its other end and connected to the other end of said shank,and means on said handle portion for actuating said tension means tocause said blade to swing on said hinge, said shank being shapable byhand to conform to the desired path of movement of said blade duringsurgery.

7. The knife set forth in claim 6 further characterized in that saidhin'ge is formed by a transverse notch in said shank which permits saidcore to bend.

8. The knife set forth in claim 6 including spaced and substantiallyparallel probes extending from said one end of said knife and formedintegrally with said shank from said malleable material, said probesbeing located at each end of said blade so as to shield the latter.

9. The knife set forth in claim 6 further characterized in that saidmalleable material is low density polyethylene.

10. The knife'set forth in claim 6 further characterized in that saidactuating means includes a shiftable trigger carried on said handleportion, said tension means comprises a flexible metal member which isrigidly attached to said trigger.

11. A surgical knife for removing meniscus in a human knee joint or thelike, said knife comprising, a malleable shank formed of low densitypolyethylene, said shank having a metal core extending therein, a steelblade fixed to one end of said core and having a cutting edge adjacentone end of said knife, a transverse notch in said shank which forms ahinge and permits said core to bend for swingably mounting said blade,tension means connected to said blade and extending along said core forswinging said blade relative to said shank; said core, blade and tensionmeans being encapsulated in said malleable material and being moldedtherein, said knife also having a handle portion at its other end andconnected to the other end of said shank, and means on said handleportion for actuating said tension means to cause said blade to swing onsaid hinge, said shank being shapable by hand to conform to the desiredpath of movement of said blade during surgery.

12. The knife set forth in claim 11 including spaced and substantiallyparallel probes extending from said one end of said knife and formedintegrally with said shank from polyethylene, said probes being locatedat each end of said blade so as to shield the latter.

13. The knife set forth in claim 11 further characterized in that saidactuating means includes a shiftable trigger carried on said handleportion, said tension means comprises a flexible metal member which isrigidly attached to said trigger.

14. The knife set forth in claim 12 including spaced and substantiallyparallel probes extending from said one end of said knife and formedintegrally with said 4 shank from said malleable material, said probesbeing located at each end of said blade so as to shield the latter.

1. A surgical knife comprising, a malleable shank having a metal coreextending therein, a cutting blade on one end of said core and having acutting edge adjacent one end of said knife, said knife also having ahandle portion at the other end of said shank, said shank being shapableby hand to conform to the desired path of movement of said blade duringsurgery.
 2. The knife set forth in claim 1 including a hinge formed insaid shank for swingably mounting said blade.
 3. The knife set forth inclaim 2 further characterized in that said hinge is formed by atransverse notch in said shank which permits said core to bend.
 4. Theknife set forth in claim 1 including spaced and substantially parallelprobes extending from said one end of said knife and formed integrallywith said shank, said probes being located at each end of said blade soas to shield the latter.
 5. The knife set forth in claim 1 furthercharacterized in that said shank is molded of low density polyethylene.6. A surgical knife comprising, a malleable shank formed of malleablematerial, said shank having a metal core extending therein, a steelblade fixed to one end of said core and having a cutting edge adjacentone end of said knife, a hinge formed in said shank for swingablymounting said blade, tension means connected to said blade and extendingalong said core for swinging said blade relative to said shank; saidcore, blade and tension means being encapsulated in said malleablematerial and being molded therein, said knife also having a handleportion at its other end and connected to the other end of said shank,and means on said handle portion for actuating said tension means tocause said blade to swing on said hinge, said shank being shapable byhand to conform to the desired path of movement of said blade duringsurgery.
 7. The knife set forth in claim 6 further characterized in thatsaid hinge is formed by a transverse notch in said shank which permitssaid core to bend.
 8. The knife set forth in claim 6 including spacedand substantially parallel probes extending from said one end of saidknife and formed integrally with said shank from said malleablematerial, said probes being located at each end of said blade so as toshield the latter.
 9. The knife set forth in claim 6 furthercharacterized in that said malleable material is low densitypolyethylene.
 10. The knife set forth in claim 6 further characterizedin that said actuating means includes a shiftable trigger carried onsaid handle portion, said tension means comprises a flexible metalmember which is rigidly attached to said trigger.
 11. A surgical knifefor removing meniscus in a human knee joint or the like, said knifecomprising, a malleable shank formed of low density polyethylene, saidshank having a metal core extending therein, a steel blade fixed to oneend of said core and having a cutting edge adjacent one end of saidknife, a transverse notch in said shank which forms a hinge and permitssaid core to bend for swingably mounting said blade, tension meansconnEcted to said blade and extending along said core for swinging saidblade relative to said shank; said core, blade and tension means beingencapsulated in said malleable material and being molded therein, saidknife also having a handle portion at its other end and connected to theother end of said shank, and means on said handle portion for actuatingsaid tension means to cause said blade to swing on said hinge, saidshank being shapable by hand to conform to the desired path of movementof said blade during surgery.
 12. The knife set forth in claim 11including spaced and substantially parallel probes extending from saidone end of said knife and formed integrally with said shank frompolyethylene, said probes being located at each end of said blade so asto shield the latter.
 13. The knife set forth in claim 11 furthercharacterized in that said actuating means includes a shiftable triggercarried on said handle portion, said tension means comprises a flexiblemetal member which is rigidly attached to said trigger.
 14. The knifeset forth in claim 12 including spaced and substantially parallel probesextending from said one end of said knife and formed integrally withsaid shank from said malleable material, said probes being located ateach end of said blade so as to shield the latter.